It is well known that an internal combustion engine is a device that mixes air and fuel in an engine for combustion to generate power. Often, in an internal combustion engine, a small quantity of blow-by gas leaks from a combustion chamber into the crankcase. Thereafter, such blow-by gas is re-supplied to the combustion chamber for re-combustion. The system provided in the engine for re-combustion of such blow-by gas is often called a positive crankcase ventilation (PCV) system.
In a common PCV system, blow-by gas is primarily supplied from the crankcase to a cylinder head through a tube passage formed between the crankcase and the cylinder head. Next, blow-by gas is supplied from the cylinder head to an intake manifold from which it is presented to a combustion chamber through an intake port of a cylinder head for re-combustion.
There usually exist engine lubricant elements, such as lubricating oil, in the blow-by gas. Therefore, if a portion of the blow-by gas path is connected with a rubber connection, the rubber connection is exposed to the lubricant. As a result, the durability of the rubber portion is shortened as the lubricant breaks down the rubber component.